Converting hydrocarbon oils



Dec. 31, 1935. p. P. BAILEY CONVERTING HYDROCARBON OILS Filed May 16,1931 INVENT ATTORNEY Patented Dec. 31, 1935 UNITED STATES PATENT OFFICE2,026,505 CONVERTING mmnooar'mon OILS tion of Delaware Application May16, 1931, Serial No. 537,816

4 Claims. (01. 196-48) This invention relates to improvements inconverting hydrocarbon oils and relates particularly to pressurecracking of petroleum oils to produce satisfactory yields of motor fuelhaving high anti-knock value while inhibiting the formation ofsubstantial quantities of free carbon or coke and non-condensable gas.

The invention broadly contemplates converting higher boiling hydrocarbonoils, such as topped crude or gas oils, into lower boiling ones atdesirably high temperatures where relatively high anti-knock values aredeveloped, and at the same time inhibiting the formation of excessquantities of coke or carbon and gas.

When operating according to the invention, portions of the heavierconstituents of the cracked products that are prevented from decomposinginto coke or gas are made available for further treatment in theprocessto be thereby further converted into desirable motor fuel.

Thus among the foremost advantages of my invention is that relativelyheavy unclean oils may be processed and, satisfactory yields of highantiknock motor fuel obtained, and continuous oper- 2 ating periods oflong duration may be had without formation of substantial quantities ofcoke and gas.

The invention includes the steps of heating a fresh charge oil to adesirable moderate crack- 0 ing temperature and delivering it into areaction and contacting vessel from which a vapor is passed to otherreaction vessels and is finally dephlegmated to produce a desirablemotor fuel and a clean gas oilcondensate. The clean gas 35 oil is heatedto a higher temperature than the fresh charge oil and is delivered intothe contacting vessel where it is contacted with the fresh charge oiland a residue which is deposited in the further reaction vessels and ispassed into 4.0 the contacting vessel. The resultant vapors are combinedand passed thru the reaction vessels and dephlegmator as described. Aresidue which is precipitated in the contacting vessel is withdrawnsubstantially as fast as it is deposited 4.5 as is also the residueprecipitating in the further reaction vessels. 'An appropriatesuperatmospheric pressure is maintained thruout the system.

Other advantages of the invention may be 50 better understood by'referring to the following description in connection with theaccompanying drawing, the single figure of which illustratesdiagrammatically a preferred embodiment of apparatus suitable forcarrying out the invention.

55 I is a heater, 2 is a combination flash and reaction vessel, 3 is aheater, 4 and 5 are reaction vessels, 6 is a dephlegmator, I is a refluxcondenser, 8 is a final condenser, 9 is a trap and I0 is an accumulator.

Oil to be treated, from a source not shown, is 5 delivered thru a line15 to the heater l and is transferred from the heater thru a line I6 toa plate or spreader near the mid-point in the vessel 2.

Vapors and mist formed in the vessel 2 are 10 delivered overhead thru aline 20 into the vessel 4 while residue deposited in the bottom of thevessel is discharged thru a line 2|.

A line 22 connects the lower portions of the vessels 4 and 5 while drainlines 23 and 24 connect with a transfer line 25 having a pump 26 whichleads to a plate or spreader near the midpoint in vessel 2.

A line 30 conducts vapors from the top of the vessel 5 into the lowerportion of the dephlegmator 6. Vapors emerging from the top of thedephlegmator pass thru a line 3| into the reflux condenser 1. A line 32conveys condensate from the condenser 1 back to the dephlegmator 6 whilea line 33conducts the issuing vapor to the final condenser 8, and a line34, from which the trap 9 depends, conveys the final products to theaccumulator H] which has a vapor outlet and a liquid outlet 36.

A line 40 having a drain connection 4|, leads to the pump 42 from whichlines 43 and 45 lead to the vessel 5 and the heater 3, respectively, anda transfer line 46 leads from the heater 3 to the vessel 2. A cooler 44is provided inthe line 43.

A pump 50 in a line 5|, leading from the bottom of the trap 9 to theupper portion of the dephlegmator 6, serves to return a portion of thedistillate as a coolant to the dephlegmator.

upwardly while the residual portion of the oil over- .50 V

flows the plate and drops down to other baffles or spreader plates whichare provided for spreading the liquid oil out film-like toafford'greatest pos- V sible contact with'hotter vapors sweeping overits surface and to minimize the possibility of parti- 5 cles of lighterproducts becoming imprisoned in the residue and carried down with it.

In addition to the charge oil the residue which is deposited in vesselst and 5 is delivered into the vessel 2 at a higher point. The residue isusually som what cooler than the charge oil when it is delivered intothe vessel 2.

Both of these oils are subjected to additional heating in this vessel bythe highly heated clean gas oil fraction which is condensed in thedephlegmator 6 and heated in the coil 3. This condensate, which may bedrawn from the dephlegmator at approximately 725 F. is passed rapidlythru the heater 3 where its temperature is raised to approximately 1000or 1050 F. and is immediately delivered to a lower point in the vessel 2than the charge oil and residue are.

Such of the charge oil and residue as does not vaporize upon enteringthe vessel 2 overflows the baflies and is subjected to further heatingby the upwardly moving highly heated vapors of the clean stock. Thisheat interchange effects further vaporization of the charge oil andresidue and also some condensation of the more highly heated cleanstock. Remaining residual portions overflow the lower baiiles and aredeposited in the bottom of the vessel from where they are withdrawnsubstantially as soon as they are deposited, only enough being held inthe bottom of the vessel to maintain a liquid seal, that is, so that noquantity of vapor will be withdrawn.

The vapor and mist developing in the vessel 2 is passed thru the vessels4 and 5 where the time of reaction of the vaporous portion is measurableby its velocity as it is passed therethru. A tempera ture ofapproximately 87 5 F. is maintained in the reaction vessel 4 andslightly less in the vessel 5. The mist and other liquid particles beingformed by polymerization and condensation undergo less time of reactionthan the vapors do as they are coalescing continuously and beingdeposited in the bottoms of the vessels and withdrawn while the vaporousportion is moved from one vessel to the next and finally released fromthe last one.

All of the vapor produced in the cracking step is subjected to scrubbingin the upper portion of the vessel 5 to remove any tarry or carbonparticles which might have been carried along to this point. It ispreferable in this scrubbing step to return a portion of the cleancondensate from the dephlegmator to one of a series of plates or balilessituated in the top of the last vessel over which the vapor sweeps. Inorder to avoid returning considerable quantities of this reflux materialit is desirable to pass it thru the cooling coil 44.

The scrubbed vapor is passed to the dephlegmator 6 where it isdephlegmated to produce a clean reflux condensate and an overhead vapor.The overhead vapor is passed thru the reflux condenser f and a finalvapor is condensed in the condenser 8 to produce a motor fueldistillate, a portion of which may be pumped back continuously to theupper portion of the dephlegmator 6 as a cooling medium. It ispreferable to keep the level of condensate drawn down to a minimum inthe dephlegmator the same as in the reaction vessels. While thetemperature of the oil at this point in the system is not high enough toeffect much cracking it is desirable that the condensate which is to beso highly heated be free of tarry or cokey substance.

In the mode of operation just described, the condensate from thedephlegmator 5 which is to be heated to the high temperature is a veryclean stock, such for example as a gas oil fraction having a color ofapproximately [5 on the Lovibond scale thru a cell.

This very clean lower boiling fraction is more difficult to convert thanthe heavier higher boiling charge oil and residue, but on the other handit is capable of withstanding higher temperatures without the advancedconversion or decomposition that produces carbon and gas. Converting atthe higher temperature serves also to produce motor fuel of relativelyhigh anti-knock value. 10 As the rate of decomposition increases rapidlywith the temperature, however, it is of advantage to lower thetemperature of this oil almost as soon as a desirably high degree hasbeen attained.

This is accomplished by the quenching effect of the cooler oil and vaporin the vessel 2. By this heat interchange an average temperature of themixture in the vessel 2 is effected at which conversion of thevoluminous vapor and mist continues at a somewhat slower butsatisfactory rate and as the rapidly precipitating liquid which isdeposited in the bottom of the vessel is withdrawn substantially as soonas it is deposited it does not have time to further decompose to formcarbon.

t is believed that the cooler quenching oil may also have a solventeffect on incipient gas and coke in the highly heated clean stock.

Due to the conditions set up in the vessel 2 it will not always bepossible to remove all of the gas oil fraction from the residual portionof the residue and charge oil which is deposited in the bottom thereof.It may therefore be desirable to subject this residue to autogenousdistillation at reduced pressure to strip it of the gas oil fractionwhich may be returned to the system with the charge oil for furthertreatment.

While I have described a rather specific mode of operation, it is to beunderstood that I do not wish to limit my invention in this manner, butprefer it to be limited only by the appended claims in which theinvention is defined.

I claim:

1. The process of converting higher boiling hydrocarbon oils into lowerboiling ones that comprises heating a condensate oil to high crackingtemperature in transit through a heating coil, passing the heated oil ata high cracking temperature into an enlarged cracking zone maintained atcracking temperature wherein separation of vapors from liquid occurs,introducing oil into said enlarged cracking zone, at a temperature lowerthan that of said condensate oil introduced, to thereby lower thetemperature of reaction therein as well as subject the cooler oil tocracking, withdrawing separated liquid from the enlarged cracking zoneat a rate adequate to prevent the accumulation of a body of liquidtherein, passing separated vapors to a secondary cracking zone whereinthe vapors are maintained at a cracking temperature to effect furthercracking of the vaporous constituents, preventing the accumulation ofliquid in said secondary cracking zone by the rapid withdrawal of liquidtherefrom, and conducting the withdrawn liquid to said enlarged crackingzone, passing the vapors to a fractionating zone and subjecting them tofractionation therein to separate out a final light distillate and areflux condensate and conducting said reflux condensate to said heatingcoil.

2. The process of converting higher boiling hydrocarbon oils into lowerboiling ones that comprises heating a condensate oil to high crackingtemperature in transit through a heating coil, passing the heated oil athigh cracking tem- 15 perature into an enlarged cracking zone maintainedat cracking temperature wherein separation of vapors from liquid occurs,separately heating charging stock to a moderate cracking temperaturelower than that to which said condensate oil is subjected in saidheating coil and directing the heated charging stock into said enlargedcracking zone, withdrawing separated liquid from said enlarged crackingzone at a rate adequate to prevent the accumulation of a body of liquidtherein, passing separated vapors to a secondary cracking zone whereinthe vapors are maintained at a cracking temperature to effect furthercracking of the vaporous constituents, preventing the accumulation ofliquid in said secondary cracking zone by the rapid withdrawal of liquidtherefrom, and conducting the withdrawn liquid to said enlarged crackingzone,

passing the vapors to a fractionating zone and subjecting them tofractionation therein to separate out a final light distillate and areflux condensate and conducting said reflux condensate to said heatingcoil.

3. The process of converting higher boiling hydrocarbon oils into lowerboiling oils which comprises heating a cracking stock to a moderatecracking temperature of the order of 825 F., passing the heated oil intoa contacting and vaporizing zone thru which evolved vapors risemaintained at a cracking temperature, drawing off vapors from the upperpart of said zone, passing them to a subsequent reaction zone forfurther reaction while maintained at cracking temperatures, withdrawingvapors from the reaction zone and subjecting them to fractionationbetween motor fuel as vapor and a heavier oil as condensate, withdrawingresidue from the reaction zone, heating the condensate to' a highcracking temperature of the order of 1000 F., and passing it into saidcontacting and vaporizing zone at a point below the point of entry ofthe heated cracking stock, passing the residue withdrawn from saidreaction zone into the contacting and vaporizing zone at a point abovethe point of entry of the heated cracking stock, ef- 5 fecting contactbetween rising vapors and falling liquid in such zone, andwithdrawing-residual liquid from the bottom of the zone at a rateadequate to prevent the accumulation of liquid therein. 10 4. Theprocess of converting higher boiling hydrocarbon oils into lower boilingones that comprises heating a condensate oil to high crackingtemperature in transit through a heating coil, discharging the heatedoil from the heating coil 15 and passing it into an enlarged crackingzone maintained at cracking temperature wherein separation of vaporsfrom liquid occurs, introducing oil into said enlarged cracking zone, ata temperature lower than that of said condensate 20 oil discharged fromsaid heating coil, to thereby lower the temperature of reaction thereinas well as subject the cooler oil to cracking, withdrawing separatedliquid from the enlarged cracking zone at a rate adequate to prevent theaccumu- 25 lation of a body of liquid therein, passing separatedvaporsto a secondary crackingzone wherein the vaporsare maintained at acracking temperature to effect further cracking of the vaporousconstituents, preventing the accumulation of '30 liquid in saidsecondarycracking zone by the rapid withdrawal of liquid therefrom, andconducting the withdrawn liquid to said enlarged cracking zone, passingthe vapors to a fractionating zone and subjecting them to fractionation5 therein to separate out a final light distillate and a refluxcondensate and conducting said reflux condensate to said heating coil.

DOUGLAS P. BAILEY. 4o

